In order to improve safety of pedestrians, joggers, workers on roadways, etc., retroreflective markings have been attached to clothing. In one common embodiment, retroreflective appliques comprising a monolayer of retroreflective elements, e.g., transparent microspheres with hemispheric reflectors, partially embedded in a layer of binder material, with adhesive backings are bonded to articles of clothing.
A problem with such appliques is that when the garment to which they are applied is laundered, a number of the retroreflective elements may be dislodged, the elements may be degraded, or the binder material may tend to discolor, e.g., turn somewhat yellow or green, resulting in undesirable discoloration of the applique. Typically, the binder layers in such appliques contain pigments such as carbon black, titanium dioxide, or flakes of metallic aluminum. In addition to imparting a desired initial coloration to the applique, these pigments serve to stabilize the color of the applique, masking discoloration of the applique when it is laundered. The pigments are sometimes referred to as a camouflage or camouflaging agent because they hide the discoloration of the binder material. In some cases, pigments provide other desired effects as well, e.g., antimony oxide imparts flame retardant characteristics to binder layers in which it is incorporated.
The loadings of pigments which are necessary to achieve the desired degree of coloration stability and camouflage, e.g., often 1 weight percent or more, may tend to reduce the flexibility of the binder layer, causing the applique to be less flexible and increasing its susceptibility to loss of retroreflective elements when flexed. In some instances, the pigment may alter the characteristics of the binder material so as to interfere with adhesion of the retroreflective elements by the binder layer. During fabrication of the applique, the pigments may settle to the retroreflective element/binder material interface, further interfering with desired adhesion. In some instances, the pigment itself is degraded, e.g., aluminum flakes tend to oxidize, particularly when laundered under high pH conditions, so as to become translucent, reducing the desired camouflaging effect.
As a result, some desired combinations of coloration and durability are not obtained.
The problem is particularly troublesome when the clothing is subjected to industrial laundering, where the conditions of laundering are often more severe than conventional home laundering. For instance, in an industrial laundry, the laundering conditions may include wash temperatures of 40.degree. to 90.degree. C. (105.degree. to 190.degree. F.) and pH of 10 to 12.5, whereas in contrast, typical conditions for home laundering may include temperatures of 4.degree. to 60.degree. C. (40.degree. to 140.degree. F.) and pH of less than 11. Also, home laundering equipment typically subjects the articles being cleaned to less rigorous handling and stress than does industrial laundry equipment.